Stimulus dimensionality effects in mental rotation

Do 3-dimensional (3-D) figures require more time to rotate mentally than do 2-dimensional (2-D) figures? This question was examined in 2 experiments incorporating 15 2-D and 15 3-D stimuli. For 3-D stimuli, block figures were used of the type used by R. N. Shepard and J. Metzler in their classic studies. For 2-D stimuli, block figures were also used, but with all cubes in a single plane, resulting in 2-D and 3-D figures matched on surface features. Three-D figures elicited steeper slopes than did 2-D figures, supporting the view that the mental rotation of visual representations is sensitive to stimulus dimensionality. The authors summarize the results of several mental rotation studies that investigated stimulus dimensionality and suggest that the evidence across studies is consistent with the present finding. They discuss 2 plausible loci for the dimensionality effect in S. M. Kosslyn's (1980) theory of mental imagery.